As more parts of the world face intense drought, new technologies are emerging to clean and reuse existing water. Investors are seeing potential for big profits.

Water treatment is expensive. It uses a lot of energy and produces its own waste that gets disposed of at a hefty price. Capture6, a startup in Berkeley, California, says it’s developing a solution, and one with an added benefit to the environment.

Capture6′s technology repurposes industrial and water treatment waste, generating clean water and capturing carbon dioxide from the atmosphere.

“That combination of water treatment, brine management, and carbon capture all at once is part of what makes us unique, what makes our process innovative,” said Capture6 CEO Ethan Cohen-Cole, who co-founded the company in 2021. “We are able to do so at reduced energy costs.”

The process is complex. It starts with the waste from any sort of water treatment process. Once the solids are removed, that waste is called brine, which is leftover water plus concentrated salt — sodium chloride. Treatment facilities usually have to pay to get rid of it.

But Capture6 takes that brine, strips out the fresh water and separates the salt into sodium and chlorine. It then turns the sodium into lye.

“That lye has the really neat property that if you expose it to the air, it will bond with CO2 and strip it from the air, and that’s the punch line to the process,” said Cohen-Cole. “We have processed the waste salt, we’ve returned fresh water to our partner, and we’ve captured CO2 from the air.”

It’s a particularly attractive proposition in areas most in need of clean water. Capture6 is working in Western Australia, South Korea, and in drought-stricken California, at the Palmdale Water District north of Los Angeles. The district is still testing the technology, but is already projecting huge cost savings in its brine management.

“It will save us 10% on that capital cost, as well as saving us 20 to 40% in operational costs,” said Scott Rogers, assistant general manager at Palmdale Water District. “We’re recovering anywhere from 94% to 98% water out of water that would just normally be wasted.”

Rogers says it’s early but when more facilities start using the technology, it will create a circular economy that can benefit the environment.

Capture6 has raised $27.5 million from Tetrad Corporation, Hyundai Motors, Energy Capital Ventures, Elemental Impact and Triple Impact Capital.

Cohen-Cole says the company’s entire process could run on renewable energy, so all of the CO2 that it captures will be net negative, improving the environment. That allows the company to generate added revenue by selling carbon credits.

It’s just one technology in a growing field of carbon capture, removal and sequestration. Others include direct air capture, burying carbon underground or injecting it into the ocean.

The Trump Administration recently canceled $3.7 billion worth of awards for new technology, including carbon capture, to fight climate change. Capture6 has received funding from the U.S. Department of Energy and from state-level sources including California, according to the company. So far, none of that has been canceled.

— CNBC producer Lisa Rizzolo contributed to this piece.

Use of low-cost e-commerce giants Temu and Shein has slowed significantly in the key U.S. market amid President Donald Trump’s tariffs on Chinese imports and the closure of the de minimis loophole, new data shows.

Temu’s U.S. daily active users (DAUs) dropped 52% in May versus March, before Trump’s tariffs were announced, while those at rival Shein were down 25%, according to data shared with CNBC by market intelligence firm Sensor Tower.

DAUs is a measure of the number of people who visit or interact with a platform every 24 hours. Monthly active users (MAUs), a measure of user engagement over a 30-day period, was also down at Temu (30%) and Shein (12%) in May versus March.

The declines were also reflected in both platforms’ Apple App Store rankings. Temu averaged a rank of 132 in May 2025, down from an average top 3 ranking a year ago, while Shein averaged a rank of 60 last month versus a top 10 ranking the year prior, the data showed.

Neither Temu nor Shein immediately responded to CNBC’s request for comment.

The user drop off comes as both Temu and Shein have pulled back on U.S. advertising spend over recent months since the Trump administration’s tariff announcements.

Trump in April announced sweeping tariffs on Chinese imports, including the end of the “de minimis” tariff exemption on May 2, which allowed companies to ship low-cost goods worth less than $800 to the U.S. tariff-free.

In May, Temu’s U.S. ad spend fell 95% year-on-year while Shein’s was down 70%.

“Temu and Shein’s decline in US ad spend was also noticeable in April, as spend decreased by 40% and 65% YoY, respectively,” Seema Shah, vice president of research and insights at Sensor Tower, said in emailed comments to CNBC.

Both Temu and Shein also altered their logistics models in the wake of tariffs, shifting away from a drop shipping model, which allowed them to send items directly from Chinese suppliers to U.S. consumers, and instead, particularly in Temu’s case, building up a network of U.S. warehouses.

Rui Ma, founder and analyst at Tech Buzz China, said such moves were also likely to have impacted the companies’ ad spend strategy and customer acquisition patterns.

“All these additional costs and regulatory hurdles are clearly hurting Chinese platforms’ U.S. growth prospects,” she wrote in emailed comments.

Tech Buzz China research from March showed that a 50% tariff would be the point at which Temu would lose most of its price advantages and find it difficult to operate. The tariff on former de minimis imports currently stands at 54%, having been lowered from 120% amid a 90-day tariff truce between the U.S. and China.

Last week, Temu’s parent company PDD Holdings reported first-quarter earnings below estimates and pointed to tariffs as a significant pressure on sellers.

Temu’s popularity has nevertheless picked up outside the U.S., with non-U.S. users rising to account for 90% of the platform’s 405 million global MAUs in the second quarter, according to HSBC.

Writing in a note last week, HSBC analysts said that was “supported by growth in Europe, Latin America, and South America.” They added that the swiftest of that growth occurred in “less affluent markets.”

“Many (Chinese platforms) are now actively redirecting their efforts toward other markets such as Europe,” Ma said.